driver core: make struct bus_type.uevent() take a const *

The uevent() callback in struct bus_type should not be modifying the
device that is passed into it, so mark it as a const * and propagate the
function signature changes out into all relevant subsystems that use
this callback.

Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230111113018.459199-16-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xen: make remove callback of xen driver void returned

Since commit fc7a6209d571 ("bus: Make remove callback return void")
forces bus_type::remove be void-returned, it doesn't make much sense for
any bus based driver implementing remove callbalk to return non-void to
its caller.

This change is for xen bus based drivers.

Acked-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Dawei Li <set_pte_at@outlook.com>
Link: https://lore.kernel.org/r/TYCP286MB23238119AB4DF190997075C9CAE39@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM
Signed-off-by: Juergen Gross <jgross@suse.com>

xen-netback: use kstrdup instead of open-coding it

use kstrdup instead of open-coding it.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Acked-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: only remove 'hotplug-status' when the vif is actually destroyed

Removing 'hotplug-status' in backend_disconnected() means that it will be
removed even in the case that the frontend unilaterally disconnects (which
it is free to do at any time). The consequence of this is that, when the
frontend attempts to re-connect, the backend gets stuck in 'InitWait'
rather than moving straight to 'Connected' (which it can do because the
hotplug script has already run).
Instead, the 'hotplug-status' mode should be removed in netback_remove()
i.e. when the vif really is going away.

Fixes: 0f4558ae9187 ("Revert "xen-netback: remove 'hotplug-status' once it has served its purpose"")
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Revert "xen-netback: Check for hotplug-status existence before watching"

This reverts commit 2afeec08ab5c86ae21952151f726bfe184f6b23d.

The reasoning in the commit was wrong - the code expected to setup the
watch even if 'hotplug-status' didn't exist. In fact, it relied on the
watch being fired the first time - to check if maybe 'hotplug-status' is
already set to 'connected'. Not registering a watch for non-existing
path (which is the case if hotplug script hasn't been executed yet),
made the backend not waiting for the hotplug script to execute. This in
turns, made the netfront think the interface is fully operational, while
in fact it was not (the vif interface on xen-netback side might not be
configured yet).

This was a workaround for 'hotplug-status' erroneously being removed.
But since that is reverted now, the workaround is not necessary either.

More discussion at
https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe.org/T/#u

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Michael Brown <mbrown@fensystems.co.uk>
Link: https://lore.kernel.org/r/20220222001817.2264967-2-marmarek@invisiblethingslab.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Revert "xen-netback: remove 'hotplug-status' once it has served its purpose"

This reverts commit 1f2565780e9b7218cf92c7630130e82dcc0fe9c2.

The 'hotplug-status' node should not be removed as long as the vif
device remains configured. Otherwise the xen-netback would wait for
re-running the network script even if it was already called (in case of
the frontent re-connecting). But also, it _should_ be removed when the
vif device is destroyed (for example when unbinding the driver) -
otherwise hotplug script would not configure the device whenever it
re-appear.

Moving removal of the 'hotplug-status' node was a workaround for nothing
calling network script after xen-netback module is reloaded. But when
vif interface is re-created (on xen-netback unbind/bind for example),
the script should be called, regardless of who does that - currently
this case is not handled by the toolstack, and requires manual
script call. Keeping hotplug-status=connected to skip the call is wrong
and leads to not configured interface.

More discussion at
https://lore.kernel.org/xen-devel/afedd7cb-a291-e773-8b0d-4db9b291fa98@ipxe.org/T/#u

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Link: https://lore.kernel.org/r/20220222001817.2264967-1-marmarek@invisiblethingslab.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

xen-netback: Check for hotplug-status existence before watching

The logic in connect() is currently written with the assumption that
xenbus_watch_pathfmt() will return an error for a node that does not
exist. This assumption is incorrect: xenstore does allow a watch to
be registered for a nonexistent node (and will send notifications
should the node be subsequently created).

As of commit 1f2565780 ("xen-netback: remove 'hotplug-status' once it
has served its purpose"), this leads to a failure when a domU
transitions into XenbusStateConnected more than once. On the first
domU transition into Connected state, the "hotplug-status" node will
be deleted by the hotplug_status_changed() callback in dom0. On the
second or subsequent domU transition into Connected state, the
hotplug_status_changed() callback will therefore never be invoked, and
so the backend will remain stuck in InitWait.

This failure prevents scenarios such as reloading the xen-netfront
module within a domU, or booting a domU via iPXE. There is
unfortunately no way for the domU to work around this dom0 bug.

Fix by explicitly checking for existence of the "hotplug-status" node,
thereby creating the behaviour that was previously assumed to exist.

Signed-off-by: Michael Brown <mbrown@fensystems.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: xen-netback: xenbus: Demote nonconformant kernel-doc headers

Fixes the following W=1 kernel build warning(s):

drivers/net/xen-netback/xenbus.c:419: warning: Function parameter or member 'dev' not described in 'frontend_changed'
drivers/net/xen-netback/xenbus.c:419: warning: Function parameter or member 'frontend_state' not described in 'frontend_changed'
drivers/net/xen-netback/xenbus.c:1001: warning: Function parameter or member 'dev' not described in 'netback_probe'
drivers/net/xen-netback/xenbus.c:1001: warning: Function parameter or member 'id' not described in 'netback_probe'

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

xen/xenbus: Add 'will_handle' callback support in xenbus_watch_path()

Some code does not directly make 'xenbus_watch' object and call
'register_xenbus_watch()' but use 'xenbus_watch_path()' instead. This
commit adds support of 'will_handle' callback in the
'xenbus_watch_path()' and it's wrapper, 'xenbus_watch_pathfmt()'.

This is part of XSA-349

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

xen/xenbus: Allow watches discard events before queueing

If handling logics of watch events are slower than the events enqueue
logic and the events can be created from the guests, the guests could
trigger memory pressure by intensively inducing the events, because it
will create a huge number of pending events that exhausting the memory.

Fortunately, some watch events could be ignored, depending on its
handler callback. For example, if the callback has interest in only one
single path, the watch wouldn't want multiple pending events. Or, some
watches could ignore events to same path.

To let such watches to volutarily help avoiding the memory pressure
situation, this commit introduces new watch callback, 'will_handle'. If
it is not NULL, it will be called for each new event just before
enqueuing it. Then, if the callback returns false, the event will be
discarded. No watch is using the callback for now, though.

This is part of XSA-349

Cc: stable@vger.kernel.org
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reported-by: Michael Kurth <mku@amazon.de>
Reported-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

xen networking: add XDP offset adjustment to xen-netback

the patch basically adds the offset adjustment and netfront
state reading to make XDP work on netfront side.

Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: support dynamic unbind/bind

By re-attaching RX, TX, and CTL rings during connect() rather than
assuming they are freshly allocated (i.e. assuming the counters are zero),
and avoiding forcing state to Closed in netback_remove() it is possible
for vif instances to be unbound and re-bound from and to (respectively) a
running guest.

Dynamic unbind/bind is a highly useful feature for a backend module as it
allows it to be unloaded and re-loaded (i.e. updated) without requiring
domUs to be halted.

This has been tested by running iperf as a server in the test VM and
then running a client against it in a continuous loop, whilst also
running:

while true;
do echo vif-$DOMID-$VIF >unbind;
echo down;
rmmod xen-netback;
echo unloaded;
modprobe xen-netback;
cd $(pwd);
brctl addif xenbr0 vif$DOMID.$VIF;
ip link set vif$DOMID.$VIF up;
echo up;
sleep 5;
done

in dom0 from /sys/bus/xen-backend/drivers/vif to continuously unbind,
unload, re-load, re-bind and re-plumb the backend.

Clearly a performance drop was seen but no TCP connection resets were
observed during this test and moreover a parallel SSH connection into the
guest remained perfectly usable throughout.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: remove 'hotplug-status' once it has served its purpose

Removing the 'hotplug-status' node in netback_remove() is wrong; the script
may not have completed. Only remove the node once the watch has fired and
has been unregistered.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: switch state to InitWait at the end of netback_probe()...

...as the comment above the function states.

The switch to Initialising at the start of the function is somewhat bogus
as the toolstack will have set that initial state anyway. To behave
correctly, a backend should switch to InitWait once it has set up all
xenstore values that may be required by a initialising frontend. This
patch calls backend_switch_state() to make the transition at the
appropriate point.

NOTE: backend_switch_state() ignores errors from xenbus_switch_state()
and so this patch removes an error path from netback_probe(). This
means a failure to change state at this stage (in the absence of
other failures) will leave the device instantiated. This is highly
unlikley to happen as a failure to change state would indicate a
failure to write to xenstore, and that will trigger other error
paths. Also, a 'stuck' device can still be cleaned up using 'unbind'
in any case.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: move netback_probe() and netback_remove() to the end...

...of xenbus.c

This is a cosmetic function re-ordering to reduce churn in a subsequent
patch. Some style fix-up was done to make checkpatch.pl happier.

No functional change.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: no need to check return value of debugfs_create functions

When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.

Cc: Wei Liu <wei.liu@kernel.org>
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: xen-devel@lists.xenproject.org
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not see http www gnu org licenses

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details [based]
[from] [clk] [highbank] [c] you should have received a copy of the
gnu general public license along with this program if not see http
www gnu org licenses

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 355 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xen-netback: add reference from xenvif to backend_info to facilitate coredump analysis

During coredump analysis, it is not easy to obtain the address of
backend_info in xen-netback.

So far there are two ways to obtain backend_info:

1. Do what xenbus_device_find() does for vmcore to find the xenbus_device
and then derive it from dev_get_drvdata().

2. Extract backend_info from callstack of xenwatch (e.g., netback_remove()
or frontend_changed()).

This patch adds a reference from xenvif to backend_info so that it would be
much more easier to obtain backend_info during coredump analysis.

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.

Warning level 3 was used: -Wimplicit-fallthrough=3

This patch is part of the ongoing efforts to enabling
-Wimplicit-fallthrough.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: xenbus: convert to DEFINE_SHOW_ATTRIBUTE

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: xenbus: remove redundant condition check before debugfs_remove_recursive

debugfs_remove_recursive has taken the IS_ERR_OR_NULL into account. Just
remove the unnecessary condition check.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: Use array_size() in vzalloc()

The vzalloc() function has no 2-factor argument form, so multiplication
factors need to be wrapped in array_size(). This patch replaces cases of:

vzalloc(a * b)

with:
vzalloc(array_size(a, b))

as well as handling cases of:

vzalloc(a * b * c)

with:

vzalloc(array3_size(a, b, c))

This does, however, attempt to ignore constant size factors like:

vzalloc(4 * 1024)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
vzalloc(
- (sizeof(TYPE)) * E
+ sizeof(TYPE) * E
, ...)
|
vzalloc(
- (sizeof(THING)) * E
+ sizeof(THING) * E
, ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
vzalloc(
- sizeof(u8) * (COUNT)
+ COUNT
, ...)
|
vzalloc(
- sizeof(__u8) * (COUNT)
+ COUNT
, ...)
|
vzalloc(
- sizeof(char) * (COUNT)
+ COUNT
, ...)
|
vzalloc(
- sizeof(unsigned char) * (COUNT)
+ COUNT
, ...)
|
vzalloc(
- sizeof(u8) * COUNT
+ COUNT
, ...)
|
vzalloc(
- sizeof(__u8) * COUNT
+ COUNT
, ...)
|
vzalloc(
- sizeof(char) * COUNT
+ COUNT
, ...)
|
vzalloc(
- sizeof(unsigned char) * COUNT
+ COUNT
, ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
vzalloc(
- sizeof(TYPE) * (COUNT_ID)
+ array_size(COUNT_ID, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(TYPE) * COUNT_ID
+ array_size(COUNT_ID, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(TYPE) * (COUNT_CONST)
+ array_size(COUNT_CONST, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(TYPE) * COUNT_CONST
+ array_size(COUNT_CONST, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(THING) * (COUNT_ID)
+ array_size(COUNT_ID, sizeof(THING))
, ...)
|
vzalloc(
- sizeof(THING) * COUNT_ID
+ array_size(COUNT_ID, sizeof(THING))
, ...)
|
vzalloc(
- sizeof(THING) * (COUNT_CONST)
+ array_size(COUNT_CONST, sizeof(THING))
, ...)
|
vzalloc(
- sizeof(THING) * COUNT_CONST
+ array_size(COUNT_CONST, sizeof(THING))
, ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

vzalloc(
- SIZE * COUNT
+ array_size(COUNT, SIZE)
, ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
vzalloc(
- sizeof(TYPE) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(TYPE) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(TYPE) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(TYPE) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(TYPE))
, ...)
|
vzalloc(
- sizeof(THING) * (COUNT) * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
vzalloc(
- sizeof(THING) * (COUNT) * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
vzalloc(
- sizeof(THING) * COUNT * (STRIDE)
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
|
vzalloc(
- sizeof(THING) * COUNT * STRIDE
+ array3_size(COUNT, STRIDE, sizeof(THING))
, ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
vzalloc(
- sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
vzalloc(
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
, ...)
|
vzalloc(
- sizeof(THING1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
vzalloc(
- sizeof(THING1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(THING1), sizeof(THING2))
, ...)
|
vzalloc(
- sizeof(TYPE1) * sizeof(THING2) * COUNT
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
|
vzalloc(
- sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+ array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
, ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
vzalloc(
- (COUNT) * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
vzalloc(
- COUNT * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
vzalloc(
- COUNT * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
vzalloc(
- (COUNT) * (STRIDE) * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
vzalloc(
- COUNT * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
vzalloc(
- (COUNT) * STRIDE * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
vzalloc(
- (COUNT) * (STRIDE) * (SIZE)
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
|
vzalloc(
- COUNT * STRIDE * SIZE
+ array3_size(COUNT, STRIDE, SIZE)
, ...)
)

// Any remaining multi-factor products, first at least 3-factor products
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
vzalloc(C1 * C2 * C3, ...)
|
vzalloc(
- E1 * E2 * E3
+ array3_size(E1, E2, E3)
, ...)
)

// And then all remaining 2 factors products when they're not all constants.
@@
expression E1, E2;
constant C1, C2;
@@

(
vzalloc(C1 * C2, ...)
|
vzalloc(
- E1 * E2
+ array_size(E1, E2)
, ...)
)

Signed-off-by: Kees Cook <keescook@chromium.org>

drivers/net: Use octal not symbolic permissions

Prefer the direct use of octal for permissions.

Done with checkpatch -f --types=SYMBOLIC_PERMS --fix-inplace
and some typing.

Miscellanea:

o Whitespace neatening around these conversions.

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fix race condition on XenBus disconnect

In some cases during XenBus disconnect event handling and subsequent
queue resource release there may be some TX handlers active on
other processors. Use RCU in order to synchronize with them.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: don't vfree() queues under spinlock

This leads to a BUG of the following form:

[ 174.512861] switch: port 2(vif3.0) entered disabled state
[ 174.522735] BUG: sleeping function called from invalid context at
/home/build/linux-linus/mm/vmalloc.c:1441
[ 174.523451] in_atomic(): 1, irqs_disabled(): 0, pid: 28, name: xenwatch
[ 174.524131] CPU: 1 PID: 28 Comm: xenwatch Tainted: G W
4.10.0upstream-11073-g4977ab6-dirty #1
[ 174.524819] Hardware name: MSI MS-7680/H61M-P23 (MS-7680), BIOS V17.0
03/14/2011
[ 174.525517] Call Trace:
[ 174.526217] show_stack+0x23/0x60
[ 174.526899] dump_stack+0x5b/0x88
[ 174.527562] ___might_sleep+0xde/0x130
[ 174.528208] __might_sleep+0x35/0xa0
[ 174.528840] ? _raw_spin_unlock_irqrestore+0x13/0x20
[ 174.529463] ? __wake_up+0x40/0x50
[ 174.530089] remove_vm_area+0x20/0x90
[ 174.530724] __vunmap+0x1d/0xc0
[ 174.531346] ? delete_object_full+0x13/0x20
[ 174.531973] vfree+0x40/0x80
[ 174.532594] set_backend_state+0x18a/0xa90
[ 174.533221] ? dwc_scan_descriptors+0x24d/0x430
[ 174.533850] ? kfree+0x5b/0xc0
[ 174.534476] ? xenbus_read+0x3d/0x50
[ 174.535101] ? xenbus_read+0x3d/0x50
[ 174.535718] ? xenbus_gather+0x31/0x90
[ 174.536332] ? ___might_sleep+0xf6/0x130
[ 174.536945] frontend_changed+0x6b/0xd0
[ 174.537565] xenbus_otherend_changed+0x7d/0x80
[ 174.538185] frontend_changed+0x12/0x20
[ 174.538803] xenwatch_thread+0x74/0x110
[ 174.539417] ? woken_wake_function+0x20/0x20
[ 174.540049] kthread+0xe5/0x120
[ 174.540663] ? xenbus_printf+0x50/0x50
[ 174.541278] ? __kthread_init_worker+0x40/0x40
[ 174.541898] ret_from_fork+0x21/0x2c
[ 174.548635] switch: port 2(vif3.0) entered disabled state

This patch defers the vfree() until after the spinlock is released.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: keep a local pointer for vif in backend_disconnect()

This patch replaces use of 'be->vif' with 'vif' and hence generally
makes the function look tidier. No semantic change.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen: modify xenstore watch event interface

Today a Xenstore watch event is delivered via a callback function
declared as:

void (*callback)(struct xenbus_watch *,
const char **vec, unsigned int len);

As all watch events only ever come with two parameters (path and token)
changing the prototype to:

void (*callback)(struct xenbus_watch *,
const char *path, const char *token);

is the natural thing to do.

Apply this change and adapt all users.

Cc: konrad.wilk@oracle.com
Cc: roger.pau@citrix.com
Cc: wei.liu2@citrix.com
Cc: paul.durrant@citrix.com
Cc: netdev@vger.kernel.org

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

xen-netback: protect resource cleaning on XenBus disconnect

vif->lock is used to protect statistics gathering agents from using the
queue structure during cleaning.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fix memory leaks on XenBus disconnect

Eliminate memory leaks introduced several years ago by cleaning the
queue resources which are allocated on XenBus connection event. Namely, queue
structure array and pages used for IO rings.

Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fix error handling output

The connect function prints an unintialized error code after an
earlier initialization was removed:

drivers/net/xen-netback/xenbus.c: In function 'connect':
drivers/net/xen-netback/xenbus.c:938:3: error: 'err' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This prints it as -EINVAL instead, which seems to be the most
appropriate error code. Before the patch that caused the warning,
this would print a positive number returned by vsscanf() instead,
which is also wrong. We probably don't need a backport though,
as fixing the warning here should be sufficient.

Fixes: f95842e7a9f2 ("xen: make use of xenbus_read_unsigned() in xen-netback")
Fixes: 8d3d53b3e433 ("xen-netback: Add support for multiple queues")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

xen-netback: prefer xenbus_scanf() over xenbus_gather()

For single items being collected this should be preferred as being more
typesafe (as the compiler can check format string and to-be-written-to
variable match) and more efficient (requiring one less parameter to be
passed).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen: make use of xenbus_read_unsigned() in xen-netback

Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of some reads from int to unsigned,
but these cases have been wrong before: negative values are not allowed
for the modified cases.

Cc: wei.liu2@citrix.com
Cc: paul.durrant@citrix.com
Cc: netdev@vger.kernel.org

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>

xen-netback: (re-)create a debugfs node for hash information

It is useful to be able to see the hash configuration when running tests.
This patch adds a debugfs node for that purpose.

The original version of this patch (commit c0c64c152389) was reverted due
to build failures caused by a conflict with commit 0364a8824c02
("xen-netback: switch to threaded irq for control ring"). This new version
of the patch is nearly identical to the original, the only difference
being that creation of the debugfs node is predicated on 'ctrl_irq' being
non-zero rather then the now non-existent 'ctrl_task'.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: retire guest rx side prefix GSO feature

As far as I am aware only very old Windows network frontends make use of
this style of passing GSO packets from backend to frontend. These
frontends can easily be replaced by the freely available Xen Project
Windows PV network frontend, which uses the 'default' mechanism for
passing GSO packets, which is also used by all Linux frontends.

NOTE: Removal of this feature will not cause breakage in old Windows
frontends. They simply will no longer receive GSO packets - the
packets instead being fragmented in the backend.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Revert "xen-netback: create a debugfs node for hash information"

This reverts commit c0c64c152389ad73306b9b0796357210ec6d32ee.

There is no vif->ctrl_task member, so this change broke
the build.

Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fix error handling on netback_probe()

In case of error during netback_probe() (e.g. an entry missing on the
xenstore) netback_remove() is called on the new device, which will set
the device backend state to XenbusStateClosed by calling
set_backend_state(). However, the backend state wasn't initialized by
netback_probe() at this point, which will cause and invalid transaction
and set_backend_state() to BUG().

Initialize the backend state at the beginning of netback_probe() to
XenbusStateInitialising, and create two new valid state transitions on
set_backend_state(), from XenbusStateInitialising to XenbusStateClosed,
and from XenbusStateInitialising to XenbusStateInitWait.

Signed-off-by: Filipe Manco <filipe.manco@neclab.eu>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: create a debugfs node for hash information

It is useful to be able to see the hash configuration when running tests.
This patch adds a debugfs node for that purpose.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: add control ring boilerplate

My recent patch to include/xen/interface/io/netif.h defines a new shared
ring (in addition to the rx and tx rings) for passing control messages
from a VM frontend driver to a backend driver.

This patch adds the necessary code to xen-netback to map this new shared
ring, should it be created by a frontend, but does not add implementations
for any of the defined protocol messages. These are added in a subsequent
patch for clarity.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: reduce log spam

Remove the "prepare for reconnect" pr_info in xenbus.c. It's largely
uninteresting and the states of the frontend and backend can easily be
observed by watching the (o)xenstored log.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: implement dynamic multicast control

My recent patch to the Xen Project documents a protocol for 'dynamic
multicast control' in netif.h. This extends the previous multicast control
protocol to not require a shared ring reconnection to turn the feature off.
Instead the backend watches the "request-multicast-control" key in xenstore
and turns the feature off if the key value is written to zero.

This patch adds support for dynamic multicast control in xen-netback.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: correctly check failed allocation

Since vzalloc can be failed in memory pressure,
writes -ENOMEM to xenstore to indicate error.

Signed-off-by: Insu Yun <wuninsu@gmail.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: add support for multicast control

Xen's PV network protocol includes messages to add/remove ethernet
multicast addresses to/from a filter list in the backend. This allows
the frontend to request the backend only forward multicast packets
which are of interest thus preventing unnecessary noise on the shared
ring.

The canonical netif header in git://xenbits.xen.org/xen.git specifies
the message format (two more XEN_NETIF_EXTRA_TYPEs) so the minimal
necessary changes have been pulled into include/xen/interface/io/netif.h.

To prevent the frontend from extending the multicast filter list
arbitrarily a limit (XEN_NETBK_MCAST_MAX) has been set to 64 entries.
This limit is not specified by the protocol and so may change in future.
If the limit is reached then the next XEN_NETIF_EXTRA_TYPE_MCAST_ADD
sent by the frontend will be failed with NETIF_RSP_ERROR.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fix a BUG() during initialization

Commit edafc132baac ("xen-netback: making the bandwidth limiter runtime settable")
introduced the capability to change the bandwidth rate limit at runtime.
But it also introduced a possible crashing bug.

If netback receives two XenbusStateConnected without getting the
hotplug-status watch firing in between, then it will try to register the
watches for the rate limiter again. But this triggers a BUG() in the watch
registration code.

The fix modifies connect() to remove the possibly existing packet-rate
watches before trying to install those watches. This behaviour is in line
with how connect() deals with the hotplug-status watch.

Signed-off-by: Imre Palik <imrep@amazon.de>
Cc: Matt Wilson <msw@amazon.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen: netback: read hotplug script once at start of day.

When we come to tear things down in netback_remove() and generate the
uevent it is possible that the xenstore directory has already been
removed (details below).

In such cases netback_uevent() won't be able to read the hotplug
script and will write a xenstore error node.

A recent change to the hypervisor exposed this race such that we now
sometimes lose it (where apparently we didn't ever before).

Instead read the hotplug script configuration during setup and use it
for the lifetime of the backend device.

The apparently more obvious fix of moving the transition to
state=Closed in netback_remove() to after the uevent does not work
because it is possible that we are already in state=Closed (in
reaction to the guest having disconnected as it shutdown). Being
already in Closed means the toolstack is at liberty to start tearing
down the xenstore directories. In principal it might be possible to
arrange to unregister the device sooner (e.g on transition to Closing)
such that xenstore would still be there but this state machine is
fragile and prone to anger...

A modern Xen system only relies on the hotplug uevent for driver
domains, when the backend is in the same domain as the toolstack it
will run the necessary setup/teardown directly in the correct sequence
wrt xenstore changes.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen/netback: Properly initialize credit_bytes

Commit e9ce7cb6b107 ("xen-netback: Factor queue-specific data into queue
struct") introduced a regression when moving queue-specific data into
the queue struct by failing to set the credit_bytes field. This
prevented bandwidth limiting from working. Initialize the field as it
was done before multiqueue support was added.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: making the bandwidth limiter runtime settable

With the current netback, the bandwidth limiter's parameters are only
settable during vif setup time. This patch register a watch on them, and
thus makes them runtime changeable.

When the watch fires, the timer is reset. The timer's mutex is used for
fencing the change.

Cc: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: Imre Palik <imrep@amazon.de>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fixing the propagation of the transmit shaper timeout

Since e9ce7cb6b107 ("xen-netback: Factor queue-specific data into queue struct"),
the transimt shaper timeout is always set to 0. The value the user sets via
xenbus is never propagated to the transmit shaper.

This patch fixes the issue.

Cc: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: Imre Palik <imrep@amazon.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: support frontends without feature-rx-notify again

Commit bc96f648df1bbc2729abbb84513cf4f64273a1f1 (xen-netback: make
feature-rx-notify mandatory) incorrectly assumed that there were no
frontends in use that did not support this feature. But the frontend
driver in MiniOS does not and since this is used by (qemu) stubdoms,
these stopped working.

Netback sort of works as-is in this mode except:

- If there are no Rx requests and the internal Rx queue fills, only
the drain timeout will wake the thread. The default drain timeout
of 10 s would give unacceptable pauses.

- If an Rx stall was detected and the internal Rx queue is drained,
then the Rx thread would never wake.

Handle these two cases (when feature-rx-notify is disabled) by:

- Reducing the drain timeout to 30 ms.

- Disabling Rx stall detection.

Reported-by: John <jw@nuclearfallout.net>
Tested-by: John <jw@nuclearfallout.net>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netback: don't store invalid vif pointer

When xenvif_alloc() fails, it returns a non-NULL error indicator. To
avoid eventual races, we shouldn't store that into struct backend_info
as readers of it only check for NULL.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: do not report success if backend_create_xenvif() fails

If xenvif_alloc() or xenbus_scanf() fail in backend_create_xenvif(),
xenbus is left in offline mode but netback_probe() reports success.

The patch implements propagation of error code for backend_create_xenvif().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: reintroduce guest Rx stall detection

If a frontend not receiving packets it is useful to detect this and
turn off the carrier so packets are dropped early instead of being
queued and drained when they expire.

A to-guest queue is stalled if it doesn't have enough free slots for a
an extended period of time (default 60 s).

If at least one queue is stalled, the carrier is turned off (in the
expectation that the other queues will soon stall as well). The
carrier is only turned on once all queues are ready.

When the frontend connects, all the queues start in the stalled state
and only become ready once the frontend queues enough Rx requests.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fix unlimited guest Rx internal queue and carrier flapping

Netback needs to discard old to-guest skb's (guest Rx queue drain) and
it needs detect guest Rx stalls (to disable the carrier so packets are
discarded earlier), but the current implementation is very broken.

1. The check in hard_start_xmit of the slot availability did not
consider the number of packets that were already in the guest Rx
queue. This could allow the queue to grow without bound.

The guest stops consuming packets and the ring was allowed to fill
leaving S slot free. Netback queues a packet requiring more than S
slots (ensuring that the ring stays with S slots free). Netback
queue indefinately packets provided that then require S or fewer
slots.

2. The Rx stall detection is not triggered in this case since the
(host) Tx queue is not stopped.

3. If the Tx queue is stopped and a guest Rx interrupt occurs, netback
will consider this an Rx purge event which may result in it taking
the carrier down unnecessarily. It also considers a queue with
only 1 slot free as unstalled (even though the next packet might
not fit in this).

The internal guest Rx queue is limited by a byte length (to 512 Kib,
enough for half the ring). The (host) Tx queue is stopped and started
based on this limit. This sets an upper bound on the amount of memory
used by packets on the internal queue.

This allows the estimatation of the number of slots for an skb to be
removed (it wasn't a very good estimate anyway). Instead, the guest
Rx thread just waits for enough free slots for a maximum sized packet.

skbs queued on the internal queue have an 'expires' time (set to the
current time plus the drain timeout). The guest Rx thread will detect
when the skb at the head of the queue has expired and discard expired
skbs. This sets a clear upper bound on the length of time an skb can
be queued for. For a guest being destroyed the maximum time needed to
wait for all the packets it sent to be dropped is still the drain
timeout (10 s) since it will not be sending new packets.

Rx stall detection is reintroduced in a later commit.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: make feature-rx-notify mandatory

Frontends that do not provide feature-rx-notify may stall because
netback depends on the notification from frontend to wake the guest Rx
thread (even if can_queue is false).

This could be fixed but feature-rx-notify was introduced in 2006 and I
am not aware of any frontends that do not implement this.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen: remove DEFINE_XENBUS_DRIVER() macro

The DEFINE_XENBUS_DRIVER() macro looks a bit weird and causes sparse
errors.

Replace the uses with standard structure definitions instead. This is
similar to pci and usb device registration.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>

xen-netback: fix debugfs entry creation

The original code is bogus. The function gets called in a loop which
leaks entries created in previous rounds.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: fix debugfs write length check

Enlarge buffer size and check input length properly, so that we don't
misuse -ENOSPC.

Note that command like "kickXXXX" is still allowed, that's one patch for
another day if we really want to be very strict on this.

Reported-by: SeeChen Ng <seechen81@gmail.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Zoltan Kiss <zoltan.kiss@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: Adding debugfs "io_ring_qX" files

This patch adds debugfs capabilities to netback. There used to be a similar
patch floating around for classic kernel, but it used procfs. It is based on a
very similar blkback patch.
It creates xen-netback/[vifname]/io_ring_q[queueno] files, reading them output
various ring variables etc. Writing "kick" into it imitates an interrupt
happened, it can be useful to check whether the ring is just stalled due to a
missed interrupt.

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: bookkeep number of active queues in our own module

The original code uses netdev->real_num_tx_queues to bookkeep number of
queues and invokes netif_set_real_num_tx_queues to set the number of
queues. However, netif_set_real_num_tx_queues doesn't allow
real_num_tx_queues to be smaller than 1, which means setting the number
to 0 will not work and real_num_tx_queues is untouched.

This is bogus when xenvif_free is invoked before any number of queues is
allocated. That function needs to iterate through all queues to free
resources. Using the wrong number of queues results in NULL pointer
dereference.

So we bookkeep the number of queues in xen-netback to solve this
problem. This fixes a regression introduced by multiqueue patchset in
3.16-rc1.

There's another bug in original code that the real number of RX queues
is never set. In current Xen multiqueue design, the number of TX queues
and RX queues are in fact the same. We need to set the numbers of TX and
RX queues to the same value.

Also remove xenvif_select_queue and leave queue selection to core
driver, as suggested by David Miller.

Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
CC: Ian Campbell <ian.campbell@citrix.com>
CC: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: Add support for multiple queues

Builds on the refactoring of the previous patch to implement multiple
queues between xen-netfront and xen-netback.

Writes the maximum supported number of queues into XenStore, and reads
the values written by the frontend to determine how many queues to use.

Ring references and event channels are read from XenStore on a per-queue
basis and rings are connected accordingly.

Also adds code to handle the cleanup of any already initialised queues
if the initialisation of a subsequent queue fails.

Signed-off-by: Andrew J. Bennieston <andrew.bennieston@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: Factor queue-specific data into queue struct

In preparation for multi-queue support in xen-netback, move the
queue-specific data from struct xenvif into struct xenvif_queue, and
update the rest of the code to use this.

Also adds loops over queues where appropriate, even though only one is
configured at this point, and uses alloc_netdev_mq() and the
corresponding multi-queue netif wake/start/stop functions in preparation
for multiple active queues.

Finally, implements a trivial queue selection function suitable for
ndo_select_queue, which simply returns 0 for a single queue and uses
skb_get_hash() to compute the queue index otherwise.

Signed-off-by: Andrew J. Bennieston <andrew.bennieston@citrix.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/*: Fix FSF address in file headers

Several files refer to an old address for the Free Software Foundation
in the file header comment. Resolve by replacing the address with
the URL <http://www.gnu.org/licenses/> so that we do not have to keep
updating the header comments anytime the address changes.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Veaceslav Falico <vfalico@redhat.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: "K. Y. Srinivasan" <kys@microsoft.com>
CC: Paul Mackerras <paulus@samba.org>
CC: Ian Campbell <ian.campbell@citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: enable IPv6 TCP GSO to the guest

This patch adds code to handle SKB_GSO_TCPV6 skbs and construct appropriate
extra or prefix segments to pass the large packet to the frontend. New
xenstore flags, feature-gso-tcpv6 and feature-gso-tcpv6-prefix, are sampled
to determine if the frontend is capable of handling such packets.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: handle IPv6 TCP GSO packets from the guest

This patch adds a xenstore feature flag, festure-gso-tcpv6, to advertise
that netback can handle IPv6 TCP GSO packets. It creates SKB_GSO_TCPV6 skbs
if the frontend passes an extra segment with the new type
XEN_NETIF_GSO_TYPE_TCPV6 added to netif.h.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: add support for IPv6 checksum offload from guest

For performance of VM to VM traffic on a single host it is better to avoid
calculation of TCP/UDP checksum in the sending frontend. To allow this this
patch adds the code necessary to set up partial checksum for IPv6 packets
and xenstore flag feature-ipv6-csum-offload to advertise that fact to
frontends.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: add support for IPv6 checksum offload to guest

Check xenstore flag feature-ipv6-csum-offload to determine if a
guest is happy to accept IPv6 packets with only partial checksum.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: transition to CLOSED when removing a VIF

If a guest is destroyed without transitioning its frontend to CLOSED,
the domain becomes a zombie as netback was not grant unmapping the
shared rings.

When removing a VIF, transition the backend to CLOSED so the VIF is
disconnected if necessary (which will unmap the shared rings etc).

This fixes a regression introduced by
279f438e36c0a70b23b86d2090aeec50155034a9 (xen-netback: Don't destroy
the netdev until the vif is shut down).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Paul Durrant <Paul.Durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: Handle backend state transitions in a more robust way

When the frontend state changes netback now specifies its desired state to
a new function, set_backend_state(), which transitions through any
necessary intermediate states.
This fixes an issue observed with some old Windows frontend drivers where
they failed to transition through the Closing state and netback would not
behave correctly.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: Don't destroy the netdev until the vif is shut down

Without this patch, if a frontend cycles through states Closing
and Closed (which Windows frontends need to do) then the netdev
will be destroyed and requires re-invocation of hotplug scripts
to restore state before the frontend can move to Connected. Thus
when udev is not in use the backend gets stuck in InitWait.

With this patch, the netdev is left alone whilst the backend is
still online and is only de-registered and freed just prior to
destroying the vif (which is also nicely symmetrical with the
netdev allocation and registration being done during probe) so
no re-invocation of hotplug scripts is required.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: xenbus.c: use more current logging styles

Convert one printk to pr_<level>.

Add a missing newline in several places to avoid message interleaving,
coalesce formats, reflow modified lines to 80 columns.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: split event channels support for Xen backend driver

Netback and netfront only use one event channel to do TX / RX notification,
which may cause unnecessary wake-up of processing routines. This patch adds a
new feature called feature-split-event-channels to netback, enabling it to
handle TX and RX events separately.

Netback will use tx_irq to notify guest for TX completion, rx_irq for RX
notification.

If frontend doesn't support this feature, tx_irq equals to rx_irq.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen-netback: enable user to unload netback module

This patch enables user to unload netback module, which is useful when user
wants to upgrade to a newer netback module without rebooting the host.

Netfront cannot handle netback removal event. As we cannot fix all possible
frontends we add module get / put along with vif get / put to avoid
mis-unloading of netback. To unload netback module, user needs to shutdown all
VMs or migrate them to another host or unplug all vifs before hand.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>¬
Signed-off-by: David S. Miller <davem@davemloft.net>

Xen: consolidate and simplify struct xenbus_driver instantiation

The 'name', 'owner', and 'mod_name' members are redundant with the
identically named fields in the 'driver' sub-structure. Rather than
switching each instance to specify these fields explicitly, introduce
a macro to simplify this.

Eliminate further redundancy by allowing the drvname argument to
DEFINE_XENBUS_DRIVER() to be blank (in which case the first entry from
the ID table will be used for .driver.name).

Also eliminate the questionable xenbus_register_{back,front}end()
wrappers - their sole remaining purpose was the checking of the
'owner' field, proper setting of which shouldn't be an issue anymore
when the macro gets used.

v2: Restore DRV_NAME for the driver name in xen-pciback.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed bit field; int have_hotplug_status_watch:1

Fixes error from sparse:
CHECK drivers/net/xen-netback/xenbus.c
drivers/net/xen-netback/xenbus.c:29:40: error: dubious one-bit signed bitfield

int have_hotplug_status_watch:1;

Reported-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

xen network backend driver

netback is the host side counterpart to the frontend driver in
drivers/net/xen-netfront.c. The PV protocol is also implemented by
frontend drivers in other OSes too, such as the BSDs and even Windows.

The patch is based on the driver from the xen.git pvops kernel tree but
has been put through the checkpatch.pl wringer plus several manual
cleanup passes and review iterations. The driver has been moved from
drivers/xen/netback to drivers/net/xen-netback.

One major change from xen.git is that the guest transmit path (i.e. what
looks like receive to netback) has been significantly reworked to remove
the dependency on the out of tree PageForeign page flag (a core kernel
patch which enables a per page destructor callback on the final
put_page). This page flag was used in order to implement a grant map
based transmit path (where guest pages are mapped directly into SKB
frags). Instead this version of netback uses grant copy operations into
regular memory belonging to the backend domain. Reinstating the grant
map functionality is something which I would like to revisit in the
future.

Note that this driver depends on 2e820f58f7ad "xen/irq: implement
bind_interdomain_evtchn_to_irqhandler for backend drivers" which is in
linux next via the "xen-two" tree and is intended for the 2.6.39 merge
window:
git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/backends
this branch has only that single commit since 2.6.38-rc2 and is safe for
cross merging into the net branch.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>